A number of methods are known for making use of sulfur compounds, such as hydrogen sulfide, carbon disulfide, carbon oxysulfide and mercaptans, contained in gases which also contain oxygen and moisture, for the production of sulfuric acid. These methods have it in common that the sulfur content of the gases must be completely oxidized to sulfur dioxide by combustion, and, depending on the concentration of the sulfur compounds in the gases, either the combustion is performed with heating oil, natural gas or other such fuels, or the gas containing the sulfur compounds is used as an oxidation gas in the roasting of sulfide ores, or else elemental sulfur is additionally burned, for the purpose of achieving a sulfur dioxide concentration that will be as constant as possible. In all cases, the gas obtained contains water vapor in addition to sulfur dioxide and oxygen; i.e., in addition to the water vapor present in the starting gas, more water vapor is produced by the combustion of the hydrogen sulfide or by the burning of the fuels containing hydrocarbons.
Such gases can be used for the production of 60% to 80% sulfuric acid without removing the water vapor (wet catalysis).
There is also a known procedure whereby, after cooling, demisting and drying, the sulfur dioxide contained in the oxygen- and water vapor-laden gases is oxidized catalytically to sulfur trioxide (dry gas catalysis) and the latter is absorbed, the end product being a 95 to 99% sulfuric acid. The preparation of these gases for contact activation involves relatively great expense. For example, the gas from the sulfur combustion must be greatly cooled, and then must be dried with concentrated sulfuric acid. Since furthermore sulfur trioxide mists are formed by the cooling, these mists must be settled prior to the drying process.
In the case of gases saturated with water vapor or containing much water vapor, a process has already been proposed in German Patent Application P 25 01 419.1, of which preliminary publication has not yet been made, in which the sulfur compounds contained in gases containing oxygen are utilized by removing the water vapor content by treating the gases with a glycol, and the dried gas, still containing sulfur compounds, is used as an oxidation gas for the burning of sulfur or for the roasting of sulfidic ores in the production of highly concentrated sulfuric acid.
When such a gas contains sulfur in the form of hydrogen sulfide compounds, water vapor is formed during the subsequent combustion or roasting in the presence of oxygen. The same is the case when the burning is performed with fuels containing hydrocarbons.